The computer mouse has become a nearly universal device for interfacing with a computer. The mouse permits a computer user to position and move a cursor on a computer screen without having to use a keyboard. The cursor can take any form, such as an arrow, vertical line, or paintbrush—any token to aid the user in interfacing with a computer by controlling the position of the token on the computer screen. The cursor is controlled by moving a mouse containing a movement sensor across a surface. The movement sensor may be provided in the form of a ball mounted to revolve within a housing; the ball contacts and rolls on a surface as the mouse is moved, as directed by the user's hand motion. Sensors detect the ball's movement and generate electronic signals that enable the computer to convert the ball's movement into cursor control.
The mouse also permits the user to interface with the computer through a selectively actuated signaling device. The signaling device, which may be a button mounted on the mouse housing that is pressed or a pad touched by the user's fingertip(s), permits the user to perform a variety of functions (sometimes in connection with the movement sensor), including placing a cursor, sweeping a defined area of text or space within an area defined by cursor movement, and operating pull-down menus.
Current mouse designs have drawbacks that render them somewhat user unfriendly. First, current mice have their signaling devices located generally on the top face of the mouse housing. Having the signaling device on the top of the mouse housing means the user cannot rest his or her fingers on the mouse without risking inadvertently operating the signaling device. Instead, the user must at all times, except when operating the signaling device, hold his or her fingers in an extended, slightly tensed position that keeps finger pressure off the mouse's signaling device. This tensed position can lead to fatigue in the user's hand, arm, and wrist, and to symptoms associated with repetitive stress injuries (also known as repetitive strain injuries or carpal tunnel syndrome).
Current mouse designs also have the movement sensor positioned in the middle or toward the front of the mouse housing. The movement sensor thus is located below the fingers, knuckles, or center of the palm of the user's hand. This positioning encourages the user to move the mouse by twisting his or her wrist, because (due to the distance between the wrist joint and movement sensor) such twisting or side-to-side flexing can be used to control cursor movement. This wrist-based cursor control is less favorable from an ergonomic standpoint than lower-arm movement, because it can lead to wrist and arm fatigue and to wrist joint symptoms associated with repetitive stress injuries.
In addition, some current mouse housing designs are not shaped to fit comfortably in the user's hand. Their top surfaces often are flat, or have two planar surfaces joined at an angle. In contrast, the human hand, when in its relaxed state, tends to be curved, with an apex at the knuckles. Current designs also often make no allowance for the natural position of the human thumb, which, in its relaxed state, tends to curve or point slightly inward, toward the palm.
Recently, efforts have been made to design mice that address some of the problems noted above. Hamling, U.S. Pat. No. 5,648,798, issued Jul. 15, 1997, and Lo, U.S. Pat. No. 5,576,733, issued Nov. 19, 1996, disclose mice in which an attempt has been made to locate the signaling devices in a position that decreases the need for the user to hold his or her fingers in an extended position. These mice only partially address this problem, however, and they also have several disadvantages. Because these mice are generally rounded, the user's fingers are only somewhat relaxed when the mice are used, and the positioning of the signaling devices on these mice only partially lessens the strain on the user's fingers. In addition, the mice of Hamling and Lo position the user's hand so that his or her palm is generally perpendicular to the work surface. Thus, the signaling devices are actuated by moving the fingertips in a plane that is generally perpendicular to the work surface. Most users are unaccustomed to such an orientation. Hamling's and Lo's vertical orientation also causes the user to position his or her wrist on the work surface, resulting in uncomfortable, awkward pressure on the wrist bone. Because the user cannot rest his or her wrist on these mice, he or she also must exert an upward force on his or her hand and arm. Finally, Hamling and Lo do not disclose positioning the movement sensor to discourage wrist motion, and thus do not address the wrist-flexing problem that is discussed herein and addressed by some embodiments of the present invention.
There is an unmet need for a more ergonomic computer mouse. Such an ergonomic mouse preferably would permit the user to operate the signaling device with his or her fingers in a relaxed, nonextended position. It further would be desirable for such a mouse to encourage cursor control through whole-arm movement, rather than wrist-twisting motions. It also would be desirable for such a mouse to be comfortable to hold, move, and actuate.